Blood purification systems, which are used for conducting hemodialysis, hemodiafiltration or hemofiltration, involve the extracorporeal circulation of blood through an exchanger having a semi permeable membrane. Such systems further include a hydraulic system for circulating blood and a hydraulic system for circulating replacement fluid or dialysate comprising the main electrolytes of the blood in concentrations close to those in the blood of a healthy subject. Most of the conventionally available blood purification systems are, however, quite bulky in size and difficult to operate. Further, the design of these systems makes them unwieldy and not conducive to the use and installation of disposable components.
The conventional design of prior art hemodiafiltration systems employs single pass systems. In single pass systems, the dialysate passes by the blood in the dialyzer one time and then is disposed. Single pass systems are fraught with a plurality of disadvantages, arising from the use of large amounts of water:                Assuming a 50% rejection rate by the R.O. (Reverse Osmosis) system, at least 1000 to 1500 ml/min of water is required.        A water purification system for providing a continuous flow of 100 to 800 ml/minute of purified water is required.        An electrical circuit of at least 15 amps is required, in order to pump 100 to 800 ml of water/minute, and        A floor drain or any other reservoir capable of accommodating at least 1500 ml/min of used dialysate and RO rejection water.        
U.S. Pat. No. 4,469,593 to Ishihara, et al discloses “a blood purification apparatus [that] includes an extracorporeal circulation system, a blood purifier provided in the system for purifying blood by dialysis or filtration through a semi permeable membrane, a circulation blood volume measuring instrument for measuring changes in a circulating blood volume within a patient's body, a control section comprising a memory for storing a program for a pattern of changes in the circulating blood volume during blood purification, the program being matched to the condition of a patient, and a regulator connected to the extracorporeal circulation system and the control section, for controlling the circulating blood volume, the regulator being controlled by the control section on the basis of the circulating blood volume measured during blood purification and the programmed amount. In this apparatus, optimum blood purification is carried out while maintaining the circulating blood volume at a prescribed level.”
U.S. Pat. No. 5,114,580 to Ahmad, et al discloses “[a] hemodialysis system that has a blood circuit and a hemofiltrate circuit interconnected at a hemofilter and an air collection chamber. If an infusion of sterile fluid to the returning blood is needed during the dialysis treatment, filtrate in the filtrate circuit is pumped back into the blood circuit. This is also done to purge the blood circuit of blood and return it to the patient at the conclusion of a dialysis treatment. A blood pump in the blood circuit incorporates a flexible vessel in conjunction with pinch valves which self expand in a controlled manner from a compressed condition to fill with blood from the patient in a suction stroke controlled by the patient's blood delivery rate. Compression of the vessel by an external member then forces the blood through the rest of the blood circuit.”
U.S. Pat. No. 6,303,036 to Collins, et al discloses “[a]n apparatus and method for hemodiafiltration . . . [that] includes a first dialyzer cartridge containing a semi-permeable membrane that divides the dialyzer into a blood compartment and a dialysate compartment. Fluid discharged from the blood compartment of the first dialyzer cartridge is mixed with sterile substitution fluid to form a fluid mixture and the mixture enters a second dialyzer cartridge. The second dialyzer cartridge contains a second semi-permeable membrane which divides the second dialyzer cartridge into a blood compartment and a dialysate compartment. Hemodiafiltration occurs in both cartridges.”
None of these systems, however, address the aforementioned disadvantages of prior art blood purification systems. Conventional systems are also less reliable because of the necessity of using a myriad of tubes comprising the fluid circuits of the purification systems, thus increasing the risks of leakage and breakage.
Further, conventional blood purification systems do not have built-in functionality to check the integrity and authenticity of the disposables employed in the system. Still further, conventional systems lack the capability to allow the user of the system to interact with a remote patient care facility.
Accordingly, there is a need for a multiple-pass sorbent-based hemodiafiltration system that lowers the overall water requirements relative to conventional systems. There is also a need for a novel manifold that can be used in a single pass sorbent-based hemodiafiltration system as well as in the multiple-pass system of the present invention, which offers a lightweight structure with molded blood and dialysate flow paths to avoid a complicated mesh of tubing. It is also desirable that the novel manifold has integrated blood purification system components, such as sensors, pumps and disposables, thus enhancing fail-safe functioning of a patient's blood treatment.